Photographic material for the silver dyestuff bleaching process

ABSTRACT

Photographic material for the silver dyestuff bleaching process is provided wherein at least one silver halide emulsion layer, containing a bleachable azo dyestuff as the image dyestuff also contains a benzselenazole-benzelenazole or benselenazolebenzthiazole carbocyanine as red-sensitizer. This photographic material is characterized by an unexpectedly high relative sensitivity, especially in the presence of polyazo dyestuffs.

United States Patent Bruengger et a1.

[ Mar. 7, 1972 [54] PHOTOGRAPHIC MATERIAL FOR THE SILVER DYESTUFF BLEACHING PROCESS [72] lnventors: Heinrich Bruengger, Basel; Carlo Boragine, Fribourg, both of Switzerland [73] Assignee: Ciba Limited, Basel, Switzerland [22] Filed: Aug. 21, 1969 [21] Appl. No.: 852,083

[30] Foreign Application Priority Data May 26, 1968 Switzerland ..12772/68 [56] References Cited UNITED STATES PATENTS 2,503,776 4/1950 Sprague ..96/ 106 X US. Cl ..96/99, 96/ l 37 Field of Search ..96/ l 09, 99

3,058,978 10/1962 Berlin et al ..96/ 106 X 3,157,507 11/1964 Bruengger et al.... ..96/99 3,255,012 6/1966 Glockner et a1. ..96/l06 X 3,348,949 10/ 1967 Bannert et a1. ..96/ 106 3,354,170 11/1967 Rosenoff ..96/ 106 X 3,410,848 11/1968 Rauch et al. ..96/106 X Primary Examiner-Norman G. Torchin Assistant Examiner-John L. Goodrow Attorney-Harry Goldsmith, Joseph G. Kolodny and Mario A. Monaco [57] ABSTRACT 11 Claims, No Drawings PHOTOGRAPHIC MATERIAL FOR THE SILVER DYESTUFF BLEACHING PROCESS The present invention provides a photographic material for the silver dyestuff bleaching process wherein at least one silver halide emulsion layer, containing a bleachable azo dyestuff as the image dyestuff also contains a red-sensitizer of formula (I) Z A Se 11,] c-oH=o-o11=o In, Y n.-.

optionally of betainelike structure, wherein A represents a hydrogen atom or an alkyl group containing 1 to 4 carbon atoms, B, and B each represents an alkyl residue containing 1 to 4 carbon atoms, an alkylcarboxylic acid residue containing 1 to 5 carbon atoms, a sulphatoalkyl residue containing 1 to 4 carbon atoms or an alkylsulphonic acid residue, wherein alkyl represents a residue of formulaC,,H and n represents an integer having a value of l to 4, it also being possible for an acid group B, or B to be present as a betainelike structure, R, and R each represents an aromatic ring system containing at most two six-membered rings and fused-on in the manner indicated by the valency lines, Y represents an anion, Z

. represents a sulphur or selenium atom and m is l in the case of a betainelike molecular structure and is 2 in the case of a nonbetainelike molecular structure.

Betainelike structures results if at least one of the residues B, and B represents a sulphatoalkyl residue or an alkylsulphonic acid residue or if B and B each represents an alkylcarboxylic acid residue. in the case of the betainelike structures the anion Y is absent since the anion is already present in the molecule of the sensitizer itself, that is to say is bonded to the N-alkyl residue of the sensitizer by a homopolar bond. In this connection zwitter ions or internal salts may be mentioned. If the residues B, and B each represents an alkyl residue or one of the two residues represents an alkyl residue and the other represents an alkyl-carboxylic acid residue, the sensitizers are of a nonbetainelike structure and the anion Y neutralizes the positive charge of the actual sensitizer molecule.

If both B, and B are alkyl residues, the dyestuffs are basic cyanine dyestuffs. If only one of the residues B, and B represents an alkyl residue and the other represents an alkylsulphonic acid residue or sulphatoalkyl residue, the dyestuffs are neutral cyanine dyestuffs. Acid cyanine dyestuffs are .present if B, and B represent acid groups, that is to say carboxylic acid-alkyl, alkylsuphonic acid or sulphatoalkyl groups. A photographic material for the silver dyestuff bleaching process which contains a red-sensitizer of formula li zif fl [5555 1] owl-( drm 1 5 wherein A represents a hydrogen atom or an alkyl group conwherein A, B 8,, R,, R,,, Z, p and Y have the meanings given above, is preferred.

The residue A in formulas (l) to (III) is in the so-called mesoposition of the trimethine chain of the molecule. A is either a hydrogen atom or a methyl, propyl, butyl or especially an ethyl residue.

The residues B, and B in formula (I) are residues of formulas (IV) alkylene-H, (V) -alkylene-COOH, (Vl) -alkylene-O-SO H or (Vll) alkyleneSO H, wherein alkylene represents an alkylene residue containing 1 to 4 carbon atoms.

The following residues may be mentioned by way of examples: methyl, ethyl, propyl, isobutyl, acetic acid, propionic acid, valeric acid, sulphatomethyl, sulphatoethyl, propylsulphonic acid or butylsulphonic acid residues.

Sensitizers which are especially valuable are those of formula (VIII) CCH= CH=C \i'/ N I 8 Hr-CH;

wherein b represents an ethyl, methylcarboxylic acid or ethylcarboxylic acid residue and A, R,, R,,, Y, Z and p have the meanings given above.

The residues R, and R in formulas (l) to (I11) and (VIII) represent ring systems which are fusedon in the manner indicated by the valency lines, which may be different from one another or identical. The residues R, and R must exhibit an aromatic character and may contain at most two six-membered rings.

R, and R may here represent the completion of, for example, the following residues: benzene or naphthalene residues tetrahydronaphthalene residues or heterocyclic residues, for example, coumarone, thianaphthene or benzo-a-pyrane residues. All these residues can, of course, possessthe most diverse substituents, such as, for example halogen atoms, al-

kyl, aryl or heterocyclic residues. Alkyl or aryl residues or for R and R are, for example, also diphenyl,'furylbenzene or thienylbenzene residues.

Red-Sensitizers of formula have proved very successful in the present use, in which formula R and R each represents a benzene or naphthalene residue which is fused-on in the manner indicated by the valency lines and is optionally substituted by halogen atoms or alkyl or alkoxy groups which each contain 1 to 3 carbon atoms, and A, B B Y, Z and p have the meanings given above.

Among such Sensitizers, those of formula are again preferred, wherein X X X and X each represents a hydrogen or halogen atom or an alkyl or alkoxy group each containing 1 to 3 carbon atoms, and A, B B Y, Z and p have the meanings given above.

Preferably, the residues X, and X, are respectively in the 6- or 7-position or in the 6- or 7'-position and the residues X and X,, are respectively in the 5 and 5-position.

At the same time, red-sensitizers of formula wherein x,, X x x,,, A, B B, and Y, z and p have the meanings given above are of especial interest.

Red-Sensitizers of formula like wherein X X X and X each represents a hydrogen atom, a chlorine atom, a methyl, methoxy or ethoxy group and A, B B Y, Z and p have the meanings give above, have proved especially valuable.

The residue Y in formulas (I) to (Ill) and (VIII) to (Xll) represents one of the usual anions used in the chemistry of the cyanine dyestuffs, these anions being known to be of minor importance for the sensitizing effect. (Compare F.M. Hamer The Cyanine Dyes and Related Compounds, chapter 10, page 296). Sensitizers with preferred anions correspond to formula (XIII) S (Z) ll z 3-1 l [(sefpil A R; l I R2 Y1 CCH=C-CH=C wherein Y, represents a halogen, thiocyanate, perchlorate, nitrate, methylsulphate, ethylsulphate or p-toluenesulphonate ion and A, B B R,, R Z and p have the meanings given above.

Especially effective red-Sensitizers correspond to formula (XIV) S Z X5 will? l [6861:] X1

C2115 Ye C-CH: -CH=C Xe \g/ N a wherein Y, B X X X X,;, Z and p have the meanings given above.

Suitable representatives of the red-Sensitizers according to formula (I) are for example, the cyanine dyestuffs of Table l below, wherein the symbols represent the following:

1: Compound offormula No.

ll: Absorption maximum measured in ethanol in nm.

Ill: Sensitization maximum measured in an exposed and developed gelatine-silver halide emulsion.

Page 15: Compound No. 55 additionally possesses an H C group in the 7-position.

Page l5: Compound No. 56 possesses a fused-on benzene ring in the 6,7position.

TABLE I-Continued Xl\ Z A Se\ X3 e C--OH=C--CH=C\ Y QB Lxz \IYT/ 1? \X4 B1 B2 I z X X; B1 A B, X3 X4 Y 11 III -O 63 0211 H -C1H5 --H 03?" f-"""" '93 6 OH; -CzH5 H CzH5 -H CH3 Br" 580 624 H -CZH5 H -CzHa 'H -OCEI3 I 584 624 0 CH3 -O2H5 H -C2H5 CH3 -CH1 590 630 -H C2H5 C2H5 CE[2-CH2-COOH -CH3 CH1 I 564 640 OH3 O2H5 C2H5 C2H5 H -CH3 I 563 660 H CH2CH2-COOH 'C2H5 C2H5 H CH3 1' 561 663 -CH3 -C2H5 V V m V H 0 CH3 I 569 660 ---CH; -CzH -C2H5 CH3CH2-COOH H CH3 1 565 660 OH3 C2Hs -C2Hs CH2-CH2COOH H O OH; I- 568 660 CH;; --C2H5 CzH5 CH2CH2-COOH CH3 ---CH3 1 565 660 CH; OH OH2CHz 'O2H5 -C;H5 H CH3 569 664 86 .e Se H --CH3 C2115 CH5 -CHr-CHz-?Hz H -0C2H5 575 665 87 Se -CH5 CH3 OHzCHz-CH; -CzH -CHgCHz-CH OH; -CH; 570 660 S 03' S 03H 88 Se H CH3 --CHz-CH2-CH2 -CzH CH5 OH3 CH3 571 665 89 SB H -0CH3 CHzCH2-'CH2 -CZH5 -C3H5 CH3 -CHz 577 670 Especially suitable representatives of the red-sensitizers of (XVI) Se formula (I) are the compounds of formulas (l), (2), (16), (51), (53), (56), (66), (68) and more especially the 0 s c=c c I e compounds of formulas (5), (6), (70), (71), (83) and (85). It follows from this that compounds which possess an N ethyl group on one nitrogen atom, a propylsulphonic acid residue or propionic acid residue on the other nitrogen atom, 40 an ethyl group in the mesoposition and chlorine atoms, methyl groups or methoxy groups as substituents in the nuclei are especially effective sensitizers in photographic material for the silver dyestuff bleaching process.

The cyanine dyestuffs which according to the invention are 45 to be used as red-sensitizers in photographic material for the silver color bleaching process are in part known or can be manufactured according to known methods which are for example, described in the book by F. M. Hamer The Cyanine (XVIII) Dyes and Related Compounds, chapters V and VI (Interscience Publishers New York 1964). Further manufacturing RI processes are, inter alia, also described in German Patent Nos. 917,330 and 929,080, French Pat. No. 1,166,246, Belgian Pat. No. 571,034 and US. Pat. No. 2,503,776.

A suitable method for the manufacture of the sensitizers of formula (I) for example, comprises condensing a quaternary cyclammonium salt of formula or condensing a compound of formula (XVII) S with a compound of formula (XIX) S e wherein A, B B R,, R Y and n have the meanings given above. r Red-sensitizers of formula (1) which contain acid groups (XVb) e which do not participate in a betainelike structure may be present as free acids or as salts, especially as alkali salts such R1 I 043113 as, for example, sodium or potassium salts.

in the silver dyestuff bleaching process an increase in the sensitivity of the individual layers is especially important if the light-sensitive silver halide layer, when being exposed, already l with a compoud of formula contains a dyestuff which reduces the effective sensitivity of the layer through absorption of the exposure light. The sensitization of such layers containing dyestuff is now rendered considerably more difficult by the fact that the dyestuffs incorporated into the layer, in addition to this sensitivity-reducing effect of the absorption, possess a strong desensitizing effect on the emulsion.

According to the invention unexpectedly high relative sensitivities are now achieved in sensitizing photographic layers for the silver dyestuff bleaching process if a cyanine dyestuff of formula (I) is added as a red-sensitizer to the silver salt emulsions containing the azo dyestuff.

Especially valuable substances are red-sensitizers of formula (l) which are capable of forming the J-bands. They are distinguished by a very characteristic sensitization band with a steep drop towards the longer wavelengths and show a sensitization maximum which is bathochromically displaced by 70 to 120 nm. relative to the absorption maximum in alcoholic solution. This formation of a polymerization band, the socalled J-band, described as a second-order sensitization, is technically valuable not only as regards the position of the sensitization maximum but also as a result of the relative sensitivities thereby achieved.

The red-sensitizers to be used according to the invention in photographic material for the silver dyestuff bleaching process have already been used as sensitizers in gelatine emulsions containing color coupling agents. These gelatine emulsions containing color coupling agents were used for the production of colored photographic images according to the chromogenic development principle. In such layers these sensitizers were distinguished by the fact that their sensitizing effect was unchanged, or at most slightly changed, by the presence of the color coupling agent. Nevertheless the fact that such sensitizers can also be successfully used in layers containing azo dyestuff for the silver dyestuff bleaching process was unforeseeable and surprising. Thus it is known that azo dyestuffs are in general more substantive in dyeing than is the case for the colorless components used as coupling agents. This is especially true of polyazo dyestuffs (which includes substantially all cyanazo dyestuffs) which reduce the sensitizing effect of the hitherto usual sensitizers. lt was, therefore, to be expected that in the case of the layers of a silver dyestuff bleaching material containing azo dyestuffs an adequate sensitizing effect of the sensitizer on the silver halide would not be achieved or that such an effect would be entirely prevented. Thus it was to be assumed that the azo dyestuff would be able to displace the sensitizer adsorbed on the silver halides or that the dyestuff would form an inactive compound with the sensitizer. The extraordinarily great improvement in the sensitivity achieved with the red sensitizers used in accordance with the invention in the presence of azo dyestuffs, especially polyazo dyestuffs, was thus completely unexpected.

It is furthermore known that azo dyestuffs are desensitizers and reduce the sensitivity achievable by ordinary cyanine sensitizers.

The high sensitivity attainable by the red-sensitizers used in accordance with the invention is also achieved in layers with azo dyestuffs which are fixed by precipitation with basic precipitants, such as, for example biguanides. This is surprising because these basic precipitants (biguanides) are known to act as desensitizers and therefore their presence in the emulsion would according to all expectations have to have an unfavorable effect on the sensitization.

Equally, especially good results are achieved when using azo dyestuffs containing phenol groups. Here it has been known for a long time that azo dyestuffs containing phenol groups interfere with the effect of the known sensitizers.

The present sensitizers can be employed independently of the nature of the silver halide used. Alongside gelatine, other colloids can also be used as layer-forming agents. The present sensitizers can furthermore not only be used in multilayer material but can, for example, also be employed in mixed grain emulsions. The emulsions can furthermore contain casting additives of various kinds, for example wetting agents, hardeners or stabilizers.

Usually, the red-sensitizers of formula (I) are used in a layer containing a bluish-green bleachable azo dyestuff.

The following examples illustrate the invention. The percentages in the examples are percentages by weight.

EXAMPLE 1 Various ethanolic solutions of sensitize'rs are added, in each case to equal parts of a silver bromide-iodide emulsion containing 53 g. of silver and g. of gelatine per 1 kg. of emulsion, at 40 C., so that a sensitizer concentration of 220 mg./mol of silver results.

Emulsion Sensitizer of Fon'nula A B C (3) D (5 E For comparison purposes, emulsions F and G are additionally manufactured, containing so-called symmetrical sensitizers which differ from the sensitizers according to the invention:

c on=z on=o \HB N (BHzCHT'COOH (XXII) SOgH OCH;

Solutions A to G are cast on a transparent film substrate with a silver application of 3 g./m. The cast layers are exposed sensitometrically behind a grey wedge with a yellow filter, and thereafter the material is developed as follows:

HOaS- l. 6 Minutes development in a bath which per liter of water contains 50 g. of anhydrous sodium sulphit'e, 0.2 g. of l-phenyl-3-pyrazolidone, 6g. of hydroquinone, 35 g. of anhydrous 3. 3 to 12 minutes dyestuff bleaching with a solution which per liter of water contains 50 to 80 g. of potassium bromide, 40 to 80 g. of thiourea, 35 to 80 g. of 30 percent strength sulphuric acid and 0.01 and 2-amino-3-oxyphenazine;

4. minutes soaking and 5 minutes bleaching of residual silver with a solution of 60 g. of crystalline copper sulphate, 80 g. of potassium bromide and ml. of percent strength hydrochloric acid per liter of water;

5. soaking, fixing and soaking as indicated under 2.

The unexposed cast films A to E are also spectrally exposed to light in a spectrosensitometer. The material is processed as previously indicated under items 1 and 2, that is to say only a black and white development is carried out.

The results are summarized in the table below. The lower value of the relative sensitivity log E represents higher sensitivity.

The sensitizers used according to the invention in emulsions A to E produce a higher sensitivity and result in a sensitization maximum which is displaced to longer wavelengths than the sensitizers in emulsions F and G employed for comparison.

For a red-sensitive emulsion in a color reproduction material, sensitization with a maximum of 600 nm. and above is generally required, preferably at 640 to 700 nm.

H30 0 C-HN-O- c O-HN 0H (XXIII) EXAMPLE 2 Various ethanol solutions of sensitizers are added in each plying 1.8 g./m. of silver. The cast films are exposed and processed as indicated in Example 1. The results are summarized in the table below.

Spectrum Color Development Emulsion Sensitization Maximum Relative Sensitivity in nm log E The sensitizers used according to the invention is emulsions A to D produce a higher sensitivity and result in a sensitization maximum which is displaced to longer wavelengths than the sensitizers in emulsion E employed for comparison purposes.

EXAMPLE 3 The procedure described in Example 2 is adopted. The following are used as sensitizers according to the invention:

Emulsion sensitizers of Formula For comparison purposes, emulsion D is additionally manufactured, containing a so-called symmetrical sensitizer of formula (XX) which differs from the sensitizers according to the 4G The compound of formula is used as a bluish-green image dyestuff. The results are summarized in the table below.

case to equal parts of a silver bromide-iodide emulsion con- I "P I Emulsion Sensitization Maximum Relative Sensitmty tamlng2l g. of silver and 90 g. of gelatme per 1 kg. of emulin nm '08 E sion, at 40 C., so that a sensitizer concentration of 200 mg./mol of silver results. A 652 I B 650 3.00 Emulsion Sensitizer of Fonnula C 650 2.72

A 1 D 570 4.04 B 2 c s) The sensitizers used according to the invention in emulsions A to C produce a higher sensitivity and result in a sensitization maximum which is displaced to longer wavelengths than the sensitizers in emulsion D employed for comparison purposes.

EXAMPLE 4 The procedure in Example 2 is adopted. The compound of formula (6) is used as a sensitizer according to the invention in emulsion A. For comparison, emulsion B is manufactured, containing the so-called symmetrical sensitizer of formula (XX). The compound of formula is used as the bluish-green image dyestuff. The results are summarized in the table below.

The sensitizer used according to the invention in emulsion A produces a higher sensitivity and results in a sensitization maximum which is displaced to longer wavelengths than the symmetrical sensitizer of emulsion B.

EXAMPLE 5 Various ethanol solutions of sensitizers are added in each case to equal parts of a silver bromide-iodide emulsion containing 53 g. of silver and 70 g. of gelatine per 1 kg. of emulsion, at 40 C., so that a sensitizer concentration of I60 mg./mol of silver results:

Emulsion sensitizer of Formula A 66 B (67) C (68) D (70) E (71) For comparison, emulsions F and G are additionally manufactured, containing so-called symmetrical sensitizers which differ from the sensitizers according to the invention.

Emulsion F: Sensitizer of formula (XX) Emulsion G: Sensitizer of formula (XXI) Subsequently, an aqueous solution of the bluish-green dyestuff of formula (XXII) is added to emulsions A to G in addition to the usual additives, for example stabilizer, wetting agent, plasticizer and hardener, in an amount which results in a dyestuff concentration of 13 g./kg. of emulsion.

Solutions A to G are cast on a transparent film substrate, applying 3 g./m. of silver. These cast films are exposed and processed as indicated in Example I.

The results are summarized in the table below. The smaller value of the relative sensitivity log E represents higher sensitivity.

to E produce a higher sensitivity and result in a sensitization maximum which is displaced to longer wavelengths than in emulsions F and G, employed for comparison.

For a red-sensitive emulsion in a color reproduction material, sensitization with a maximum of 600 nm. and above is generally required, preferably at 640 to 700 nm.

sion, at 40 C., so that a sensitizer concentration of I50 mg.,/mol of silver results.

Emulsion Sensitizer of Formula A (66) B (68) C (70) D (71) For comparison, emulsion E is also manufactured, containing a so-called symmetrical sensitizer of formula (XX), which differs from the sensitizers according to the invention.

Subsequently, an aqueous solution of the bluish-green dyestuff of formula (XXII) is added to emulsions A to E in addition to the usual additives, for example stabilizers, wetting agents, plasticizers and hardeners, in an amount which results in a dyestuff concentration of 4 g./kg. of emulsion.

Solutions A to E are cast on an opaque-white substrate, applying l.8 g./m. of silver. The exposure and processing of these cast films takes place as indicated in Example 5. The

results are summarizedin the table below.

. Spectrum Color Development Emulsion Sensitization Maximum Relative Sensitivity in nln log E A 630 3.30 B 630 3.22 C 660 3.0! D 650 3.22

The sensitizers used according to the invention in emulsions A to D produce a higher sensitivity and result in a sensitization maximum which is displaced to longer wavelengths than the sensitizer in emulsion E employed for comparison.

EXAMPLE 7 The procedure described in Example 6 is adopted. The compound of formula (68) is used as the sensitizer according to the invention. For comparison, emulsion B is manufactured, containing the so-called symmetrical sensitizer of formula (XX). The compound of formula (XXIII) is used as the bluish-green image dyestuff. The results are summarized in the table below.

Spectrum Color Development Emulsion Sensitization Maximum Relative Sensitivity in nm log E 5 The sensitizer used according to the invention emulsion A produces a higher sensitivity and results in a sensitization maximum which is displaced to longer wavelengths than the symmetrical sensitizer of emulsion B.

EXAMPLE 8 The procedure described in Example 6 is adopted. The fol lowing are used as sensitizers according to the invention.

Emulsion Sensitizer of Formula 10 A B C (68) o 70 E 7| For comparison, emulsions F and G are additionally manufactured, containing so-called symmetrical sensitizers which differ from the sensitizers according to the invention.

Emulsion F: Sensitizer of formula (XX) Emulsion G: Sensitizer of formula (XXI) The compound of formula (XXIV) is used as the bluishgreen image dyestuff.

The results are summarized in the table below.

Spectrum Emulsion Sensitization Maximum in nrn A 640 B 600 c 640 o 660 E 650 The sensitizers used according to the invention in emulsions A to E result in a sensitization maximum which is displaced to longer wavelengths than the sensitizers employed for comparison purposes.

EXAMPLE 9 The procedure described in Example I is adopted. The following are used as sensitizers according to'the invention.

. Emulsion Sensitizer of Formula C p (4s) E F 3) G H l J (as) 60 For comparison, emulsions K and L are additionally'manufactured, containing so-called symmetrical sensitizers which differ from the sensitizers according to the invention.

Emulsion K: Sensitizer of formula (XXV) Emulsion L: Sensitizer of formula (XXVI) cc H=C CH: 1 9

zH5 C2H5 (XXV I) 02 a (I \MHJM/ 01 g?/ \N (EzHg H- CH COOE The results are summarized in the table below.

Spectrum Color Development Emulsion Sensitization Maximum Relative Sensitivity in nm log E.

A 655 4.20 B 655 4.32 C 650 4.46 D 660 3.6I E 655 4.01 F 650 4.28 G 665 4.01 H 650 4.26 l 665 3.92 J 665 3.55

The sensitizers used according to the invention in emulsions A to J produce a higher sensitivity, and in part result in a sensitization maximum which is displaced to longer wavelengths than the sensitizers of emulsions K and L employed for comparison.

EXAMPLE 10 The procedure described in Example 1 is adopted. The following are used as sensitizers.

Emulsion Sensitizer of Fonnula A (l6) B (39) C (40) D 5) E (5|) F (53) G 5) H (56) l 7) .l 3) K L (XXV) for comparison The dyestuff of 1 formula (XXIII) is used as the image dyestuff, and in particular so as to result in a dyestuff concentration of 24 g./kg. of emulsion.

The results are summarized in the table below.

Color Development The sensitizers employed according to the invention in emulsions A to K produce a higher sensitivity and in part result in a sensitization maximum which is displaced to longer wavelengths than the sensitizer of emulsion L employed for comparison.

EXAMPLE 1 1 The procedure described in Example 2 is adopted. The following are used as sensitizers according to the invention.

Emulsion Sensitizer of Formula A (16) B (39) C (40) D (45) E (5 I) F (53) G (55) H (56) l .I (83) K (85) L (XXV) for comparison The results are summarized in the table below.

The sensitizers employed according to the invention in emulsion A to K produce a higher sensitivity and in part result in a sensitization maximum which is displaced to longer wavelengths than the sensitizer of emulsion L employed for comparison.

EXAMPLE 12 The procedure described in Example 2 is adopted. The following are used as sensitizers.

Emulsion Sensitizer of Formula A (l6) 8 (39) C D (45) E (5! F (55) G (56) H (5 l (83) J (85) K (XXV) for comparison L (XXVI) for comparison The compound of formula (XXlll) is used as the bluishgreen image dyestuff.

The results are summarized in the table below.

The sensitizers used according to the invention in emulsions A to I produce a higher sensitivity and in part result in a sensitization maximum which is displaced to longer wavelengths than the sensitizers of the emulsions K and L employed for comparison.

We claim:

1. Photographic material for the silver dyestuff bleaching process which in at least one red-sensitive silver halide emulsion layer contains a bleachable azo dyestuff as the image dyestuff, wherein this layer contains a red-sensitizer characterized by an absorption maximum above about 554 nm. and a sensitization maximum above about 625 nm. of the formula in which A is a hydrogen atom or an alkyl group containing 1 to 4 carbon atoms; B, and B each is a member selected from the group consisting of an alkyl radical containing 1 to 4 carbon atoms, an alkylcarboxylic acid radical containing 1 to 5 carbon atoms, a sulfatoalkyl radical containing 1 to 4 carbon atoms and an alkylsulfonic acid radical, wherein alkyl is a radical of the formula -C, H and n is an integer of at most 4, provided that each of B and B is not simultaneously an acid group, R and R, each is an aromatic ring system containing at most two six-membered rings which is fused-on in the manner indicated by the valency lines; Y is an anion and Z is a sulfur or selenium atom.

2. Photographic material as claimed in claim 1, in which A is ethyl.

in which B is an ethyl, methylcarboxylic or ethylcarboxylic acid radical and B is ethyl.

4. Photographic material as claimed in claim 1, which con- 8. Photographic material as claimed in claim 1, which contains a red-sensitizer of formal; W

' tains a red-sensitizer of formula Z Se X3 A S Se C-GE=( JGH=C e i hHa Y CCH=GCH=C 19 X2 X4 \Q N B1 B2 (1;

2B5 OHgCHzCOOH in which X X X and X each is a hydrogen atom, halogen atom alkyl or alkoxy group which each contains 1 to 3 carbon 9. Photographic material as claimed in claim 1, which conatoms' tains a red-sensitizer of formula 5. Photographicmaterial as claimed in claim 4, which con- 1 5 tains a red-sensitizer of formula Q/ X N I CIIgCHgCHzSOa 02m 6. Photographic material as claimed in claim 5. in which 10. Photographic materialas claimed in claim 1, which con- X X X and X4 each is a hydrogen atom. a chlorine tainsared-sensitizerof formula atom. a methyl, methoxy or ethoxy group.

in which X X X and X each is a hydrogen atom, a 35 chlorine atom a methyl, mehoxy or ethoxy group 11. Photographic material as claimed in claim 1, which con- 7. Photographic material as claimed in claim 5, which contains a red-sensitizer of formula I N X4 B; (7 11 2 5 CHzCHzCOOH tains a red-sensitizer of formula W We 7 V Y L TEL-59/E 2 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 1 Patent No. Dated March 9 Inventofls) HEINRICH BRUENGGER ET AL It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 18, line 53, "Y""" should be Y Column 18, lines 57-64, delete the formula.

Column 18, lines 66-73, delete the formula.

Signed and sealed this 5th day of September 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

2. Photographic material as claimed in claim 1, in which A is ethyl.
 3. Photographic material as claimed in claim 1,
 4. Photographic material as claimed in claim 1, which contains a red-sensitizer of formula
 5. Photographic material as claimed in claim 4, which contains a red-sensiTizer of formula
 6. Photographic material as claimed in claim 5,
 7. Photographic material as claimed in claim 5, which contains a red-sensitizer of formula
 8. Photographic material as claimed in claim 1, which contains a red-sensitizer of formula
 9. Photographic material as claimed in claim 1, which contains a red-sensitizer of formula
 10. Photographic material as claimed in claim 1, which contains a red-sensitizer of formula
 11. Photographic material as claimed in claim 1, which contains a red-sensitizer of formula 